Are there any risks? If you take more than 1,000 micrograms per day, you may have stomach upset, muscle weakness, fatigue, and numbness or tingling in the feet or hands (peripheral neuropathy). A study found that people who took 200 micrograms of selenium per day were more likely to develop type 2 diabetes. While it’s unclear whether selenium can contribute to type 2 diabetes developing, selenium supplements aren’t recommended for people who’ve been diagnosed with diabetes.

What does the research show? Clinical trials are looking at the possible role of selenium in reducing the risk of breast cancer. One study suggested that selenium may help reduce treatment-related lymphedema. Selenium may reduce hair loss, abdominal pain, and loss of appetite in ovarian cancer patients who are getting chemotherapy.